Interfacial Engineering Using C-3 Alkyl Linker-Based Carbazole-Derived SAM Layers to Achieve 41.77% Indoor Efficiency...

Area of Science:

• Materials Science
• Photovoltaics
• Organic Electronics

Background:

• Self-assembled monolayers (SAMs) are crucial for enhancing perovskite solar cell (PSC) performance by improving hole extraction and minimizing interfacial energy losses.
• Previous research predominantly utilized SAMs with even-numbered carbon linkers (2, 4, 6 carbons) between carbazole and phosphonic acid moieties.
• The role of odd-numbered carbon linkers in SAMs for PSCs remains underexplored.

Purpose of the Study:

• To investigate the efficacy of carbazole-derived phosphonic acid SAMs with a 3-carbon (n-propyl) linker in perovskite solar cells.
• To evaluate the performance of SAMs with varying substituents (H, methoxy, phenyl) on the carbazole unit.
• To assess the potential of these SAMs as stand-alone hole-selective layers in p-i-n device architectures.

Main Methods:

• Synthesized and characterized three novel SAMs with a 3-carbon linker: 3C-H, 3C-OMe, and 3C-Ph.
• Fabricated wide bandgap (WBG) Cs$_{0.18}$FA$_{0.82}$Pb(I$_{0.8}$Br$_{0.2}$)$_3$ perovskite solar cells using these SAMs as hole-selective layers on ITO/NiO$_{x}$ substrates.
• Tested device performance under standard AM 1.5G illumination and indoor lighting conditions.

Main Results:

• The 3C-Ph SAM demonstrated superior performance, achieving a power conversion efficiency (PCE) of 21.59% under AM 1.5G illumination (V$_{OC}$ = 1.23 V, J$_{SC}$ = 21.53 mA cm$^{-2}$).
• Under indoor lighting, the 3C-Ph based PSCs exhibited a high PCE of 41.77% (V$_{OC}$ = 1.09 V, J$_{SC}$ = 280.37 µA cm$^{-2}$, FF = 81.43%).
• The study highlights the effectiveness of odd-numbered carbon linkers in SAMs for advanced solar cell applications.

Conclusions:

• Carbazole-derived phosphonic acid SAMs with a 3-carbon linker, particularly the 3C-Ph variant, are highly effective hole-selective layers for PSCs.
• These SAMs significantly enhance device performance under both standard and indoor light conditions, demonstrating versatility.
• The findings open new avenues for designing efficient SAMs for perovskite solar cells and optoelectronic devices.